1. Field of the Invention
The present invention relates to an optical fiber switch member and optical fiber switching circuits used for an optical fiber communications system. More particularly, it relates to an optical fiber switch circuit composed of at least one N.times.2N (N&gt;1) switch optical fiber member capable of switching the connections of an N number of switches at the same time by a single actuator.
2. Description of the Related Art
A 1.times.2 optical fiber switch, such as the one disclosed in U.S. Pat. No. 5,434,936 is known. First and second fixed optical fibers are adhesively fixed on the bottoms of oppositely provided V grooves in such a manner that the distal end surfaces thereof are aligned. The outer surfaces of movable optical fibers are provided with films made of a magnetic material, the portions provided with the films made of the magnetic material being disposed in a magnetic field of a permanent magnet. The portions coated by the films are driven and displaced toward the first and second fixed optical fibers alternately by changing the magnetic force acting on the films made of the magnetic material by actuators constituted by the permanent magnet and a solenoid coil, thus switching the connection.
Referring to FIG. 7, an optical fiber switch circuit constructed using the 1.times.2 optical fiber switchs mentioned above will be described. FIG. 7 shows the circuit corresponding to a case constituted by connecting seven 1.times.2 optical fiber switches.
In FIG. 7, the movable optical fibers of 1.times.2 optical fiber switches 201 through 207 are driven by actuators making use of the foregoing solenoid coils and magnetism.
A typical way to construct an optical fiber switch circuit switch members each having one input and 4 outputs employing such 1.times.2 optical fiber switches, is to connect seven 1.times.2 optical fiber switches in series as illustrated in FIG. 7. The optical fibers of the 1.times.2 optical fiber switches are connected by optical connectors or electric discharge fusion between the fibers.
The connection of the optical fiber switch of FIG. 7 is made as set forth below. To connect a port A with a port #1, the movable optical fibers of the 1.times.2 optical fiber switches 201, 202, and 204 are respectively connected to the upper fixed optical fibers as illustrated. To connect the port A with a port #5, the movable optical fibers of the 1.times.2 optical fiber switch 201 is connected to the lower fixed optical fiber, and the movable optical fibers of the 1.times.2 optical fiber switch is 203 and are connected to the upper fixed optical fibers. The switching operation is accomplished by switching the polarity of the current flowing through the solenoid coil of the actuator provided for each of the 1.times.2 optical fiber switches 201 through 207.
Hence, the optical fiber switch circuit configured as described above requires seven 1.times.2 optical fiber switches, seven control and drive circuits together with wiring therefor, and the connections of six pairs of optical fibers. This inevitably requires a large space for housing the switches themselves and their associated components and also leads to complicated wiring. Likewise, an optical fiber switch circuit having one input and 16 outputs requires fifteen 1.times.2 optical fiber switches, fifteen control and drive circuits together with wiring therefor and the connections of fourteen pairs of optical fibers. An optical fiber switch circuit having one input and 32 outputs requires thirty-one 1.times.2 optical fiber switches, thirty-one control and drive circuits together with wiring therefor and the connection of thirty pairs of optical fibers.
FIG. 8 shows the configuration of an optical fiber switch circuit having 2 inputs and 8 outputs. This optical fiber switch circuit is constituted by two pairs of optical fiber switch circuits each having one input and 4 outputs, namely, the optical fiber switch circuit comprised of three 1.times.2 optical fiber switches 208, 210, and 211, and the 1.times.4 optical fiber switch circuit comprised of three 1.times.2 optical fiber switches 209, 212, and 213 as illustrated. The optical fiber switch circuit configured as described above requires six 1.times.2 optical fiber switches, six control and drive circuits and wiring therefor, and the connections of four pairs of optical fibers. Hence, as in the case of the foregoing optical fiber switch, circuit the sizes of the switches themselves respectively equipped with actuators increase, the wiring becomes complicated, and the number of connections of the optical fibers also increases.
FIG. 9 shows an optical fiber switch circuit, namely, a 4.times.4 matrix optical fiber switch circuit having 4 inputs and 4 outputs constituted by employing eight optical fiber switch members each having one input and 4 outputs. Each of reference numerals 214 through 221 is a composed of three 1.times.2 optical fiber switches. Sixteen optical fibers 222 are provided and connected as illustrated. The 4.times.4 matrix optical fiber switch shown in FIG. 9 is a matrix optical fiber switch circuit that has a function for connecting the optical fibers of an arbitrary port A, B, C, or D in the left column to an arbitrary port #1, #2, #3, or #4 in the right column. The 4.times.4 matrix optical fiber switch circuit requires twenty-four 1.times.2 optical fiber switches and a circuit wiring for connecting twenty-four actuators.
Thus, the optical fiber switch circuits shown in FIGS. 7-9 pose a problem in that the size of the switch itself inevitably increases, the control and drive circuit and the wiring becomes more complicated, and the number of connections of optical fibers also increases as the number of the switching circuits increases.
The optical fiber switches employed for the optical fiber switch circuits described above are publicly known; however, the connection of the respective circuits has been made by the inventor and is not known to have been described previously. Therefore, the connection of the respective optical fiber switch circuits is not considered prior art.